The first episode was recorded in September 1963 on 405-line black and white videotape. However, due to several technical and performance errors in the initial recording, creator Sydney Newman and producer Verity Lambert decided to rerecord the episode. A remount was made in October, when subtle revisions were made to the Doctor's characterization.

The launch of Doctor Who was overshadowed by the assassination of John F. Kennedy the previous day. The serial received favourable reviews and the four episodes attracted an average of 6 million viewers.

The first episode starts in a junkyard in contemporary London and introduces the four characters who were to form the core of the first year's production: the Doctor, schoolteachers Ian Chesterton and Barbara Wright, who are concerned about one of their pupils at Coal Hill School named Susan Foreman, who seems to have a very alien outlook on England.

Susan is precocious, but seems to have strange gaps in her understanding of the world, which the teachers have come to her listed address, number 76 Totters Lane, to investigate. Here they encounter a police box, the programme's main prop, known as the TARDIS, from within which they hear Susan's voice. At that time, the boxes were a common sight in Britain, but only police officers held a key to enter them. The TARDIS proves to be no ordinary police box: when Ian and Barbara enter, they discover it to be much bigger on the inside than the outside, and furnished with futuristic-looking controls. The time machine retains its outward appearance when it travels through time, which Susan explains as a malfunction in the circuitry that is supposed to adapt its appearance to its surroundings.

Susan lives with her grandfather, the mysterious Doctor, who does not otherwise identify himself. He is a cranky, hostile, suspicious old man who appears to be a fugitive. Fearing that Barbara and Ian will give away the secret of the TARDIS and make life impossible for him in London, he sets the TARDIS in flight and ends up in the Stone Age.

In the remaining three episodes, the four become involved in a brutal power struggle within a Stone Age tribe. In "The Cave of Skulls", the group encounters a Paleolithic tribe and are subsequently imprisoned by them in a large cave. In "The Forest of Fear", they are shown to escape from the settlement, but are subsequently intercepted before reaching the TARDIS. They barely escape with their lives by exploitation of Ian's knowledge of how to produce fire, which induces fear and respect in the primitive Stone Age society. The final episode, "The Firemaker", has the group mediating separate factions of the tribe before fleeing successfully to the TARDIS. They travel, seemingly at random, to a new destination; even the Doctor does not know where. The TARDIS's view screen shows a mysterious forest that the Doctor declares "could be anywhere", which acts as a teaser for the next story. As the time travellers leave their machine, a radiation meter is shown on the console of the machine, unheeded by them, registering "Danger".

The serial that became An Unearthly Child was originally commissioned from writer Anthony Coburn in June 1963, when it was intended to run as the second Doctor Who serial. At this stage, it was planned that the series would open with a serial entitled The Giants, to be written by BBC staff scriptwriter C. E. Webber.[4] Webber had been heavily involved in the brainstorming meetings which had led to the creation of Doctor Who, and—with BBC Head of Drama Sydney Newman and Head of Serials Donald Wilson—had co-written the initial format document for the series.

By the middle of June, however, Wilson and Doctor Who's initial "caretaker producer" Rex Tucker decided to reject The Giants. This was partly because it was felt the serial lacked the necessary impact for an opener, and partly because it was felt that the technical requirements of the storyline—which involved the leading characters being drastically reduced in size—would be beyond the capacities of the young series at this point, given the facilities available.[5] Due to the lack of scripts ready for production, it was decided to move Coburn's serial up to first place in the running order.[5]

By the end of June, responsibility for getting Doctor Who off the ground was handed over to producer Verity Lambert and script editorDavid Whitaker, neither of whom were greatly impressed with Coburn's serial as a series 'opener'. The writer was asked to carry out major rewrites.[6] Some consideration was even given to dropping the scripts altogether, with writer Terence Dudley briefly sounded out about providing a replacement, but a lack of time necessitated Coburn's serial going ahead.[6]

The moving up in the schedule of Coburn's story necessitated his rewriting the opening episode to include some introductory elements of Webber's script for the first episode of The Giants; as a result, Webber received a co-writer's credit for the episode "An Unearthly Child" on internal BBC documentation.[7] Coburn did, however, make several significant original contributions of his own, most notably that the Doctor's time machine should externally resemble a police box, which subsequently went on to become one of the main icons of the show. Coburn had the idea for the design when he came across a real police box while on a walk near his office.[7] Concerned to avoid any possibility of sexual impropriety implicit in having a young girl travelling with an older man, Coburn also insisted that the character of Susan Foreman should be redrawn as the Doctor's granddaughter, rather than simply his travelling companion.

The serial as a whole was originally to have been directed by Rex Tucker, but when he moved on from the series, young staff director Waris Hussein, who had been attached to Doctor Who from an early stage, was given the assignment.[7] Some of the pre-filmed inserts for the serial, shot at Ealing Studios in September[8] and early October, were directed by Hussein's production assistant, Douglas Camfield.[9] The incidental music score was provided by Norman Kay. The scenic designer assigned to the serial was Peter Brachacki, who originated the distinctive TARDIS interior set, but he eventually handled only the very first episode before being replaced by Barry Newbery, as he was unhappy working on the programme.[7]

The early series, says cultural scholar John Paul Green, "explicitly positioned the Doctor as grandfather to his companion Susan."[10] Unlike most Doctor Who episodes, the Doctor is accompanied in the TARDIS by not only one companion, Susan, but also her school teachers, Ian and Barbara (William Russell and Jacqueline Hill). Scholar John R. Cook reflects that the teachers' presence echoes Doctor Who's original educational remit.[11] The New Scientist reflected, in 1982, that the serial was set in the stone age because the show's original intention was "to bring to life the Earth's history."[12]

The first version of the opening episode was recorded at Lime Grove Studios on the evening of 27 September 1963, following a week of rehearsals. The second attempt at the opening episode was recorded on 18 October, with the following three episodes being recorded weekly from that point onwards on 25 October, 1 November and 8 November.[7] As with much British television of the era, the episodes were predominantly videotaped "as live", with little scope for re-takes or breaks in recording. This left room for the many mistakes that are evident in the serial, but did allow the episodes to be completed very quickly.

The first episode, "An Unearthly Child", was originally recorded a month before full recording on the series began. However, the initial recording was bedevilled with technical problems and errors made during the performance. A particular problem occurred with the doors leading into the TARDIS control room, which would not close properly, instead randomly opening and closing through the early part of the scene. Two versions of the scene set in the TARDIS were recorded, along with an aborted first attempt to start the second version.

Sydney Newman, after viewing the episode, met producer Verity Lambert and director Waris Hussein. He indicated the many faults he found with the episode and ordered that it be mounted again; a consequence of this was the delay of the show's planned 16 November 1963 premiere date. This initial episode is now known as the unaired "pilot episode", although it was never intended as such, since the practice of producing pilot episodes did not exist in Britain in the 1960s.

During the weeks between the two tapings, changes were made to costuming, effects, performances, and the script (which had originally featured a more callous and threatening Doctor and Susan doing strange things like flicking ink blots onto paper). Changes made before the final version were filmed include a thunderclap sound effect being deleted from the opening theme music; Susan's dress being changed to make her look more like a schoolgirl than the original costume, which made her appear more alien and sensual; the Doctor's costume being changed from a contemporary jacket and tie to his familiar Edwardian clothing; a reference to the Doctor and Susan being from the 49th century was replaced with the line "[from] another time, another world"; the TARDIS door being repaired so that it closed properly; and a refinement of the TARDIS sound effect.

The original episode was not broadcast until 26 August 1991, when the BBC aired a version that edited together the first half of the taping with one of the two completed second halves. As it happened, the version chosen was the one in which the TARDIS doors would not close; other errors included actress Carole Ann Ford fluffing a line of dialogue, Jacqueline Hill getting caught in a doorway, a camera banging into a piece of scenery during one of the scrapyard sequences, and William Russell accidentally knocking over a mannequin in the scrapyard. Earlier, in June 1991, a version with the first half edited together with the other take of the second half of the pilot was released on the VHS compilation The Hartnell Years;[13] later, in 2000, the complete version (including both takes) was released in a remastered form on VHS, along with The Edge of Destruction.[14] In 2006, the Doctor Who: The Beginning DVD set contained two versions of the episode: an unedited studio recording including all takes of the second part of the show, and a newly created version of the pilot that uses the best footage from the original recording, with additional editing and digital adjustments to remove blown lines, technical problems, and reduce studio noise. Like the other episodes from this serial, both versions of the "pilot" were remastered for DVD release, using VidFIRE technology that simulated the original video look of the 1963 production.

As was usual at the beginning of the series' history, no overall title appeared on-screen, and each episode has its own title. 100,000 BC is the title that was used by the production team at the time of transmission. However, due to the absence of an overall onscreen title for the four-episode storyline, reference works have used various titles, some originating from the BBC Production Office and others seemingly invented by fans.

The Tribe of Gum: An early working title which was used up until the beginning of recording. It survived in a few documents derived from earlier paperwork, such as the payments for overseas sales, and started appearing again in reference works in the late 1970s and 1980s, including being used when the transcript of the serial was published by Titan Books.

100,000 BC: The first-known use is a publicity release dating from when the story was being recorded, and this title is used on subsequent lists and publicity releases.

The Palaeolithic Age: Used by producer Verity Lambert in a letter to a viewer in late 1964.

The Stone Age: Used on the biography listing on a publicity release for a later story in late 1965.

An Unearthly Child (or variants thereof): The title of the first episode, used by the 1973 Radio Times Tenth Anniversary Special and subsequently by the 1976 edition of The Making of Doctor Who, with much subsequent commercial use, including the novelisation, VHS and DVD releases of the story.

Many documents lack any title at all (whereas for later stories they are clearer), including the 1974 BBC Enterprises listing A Quick Guide to Doctor Who, which was the main source of titles for most early fan reference works.

Which title should be used is a subject that has generated controversy amongst fans of the series. Fan researchers such as David J. Howe argue that since 100,000 BC was used by the production team at the time of transmission, it is the most accurate title. However, the BBC markets the story as An Unearthly Child. Consequently, this became the most common title used for the story.

Scholar Mark Bould discusses how the serial establishes Doctor Who's socio-political stances. He writes, "The story represents the separation/reunion, capture/escape, pursuit/evasion that will dominate the next twenty-six years, as well as the program's consistent advocacy of the BBC's political and social liberalism." He cites Ian and Barbara's attempt to teach a cavewoman kindness, friendship and democracy, writing "a tyrant is not as strong as the whole tribe acting collectively".[16]

Lawrence Miles and Tat Wood argue that the cavemen's focus on fire is meant to stand in for all technology, thus linking the latter three episodes with the questions of generational change raised by the first episode and its focus on suspicion of children, and tying that to a discussion of technological progress, including the nuclear bomb. They also argue that, contrary to the tendency to treat the story as a one-episode introduction to the series followed by "three episodes of running around and escaping" that the piece should be considered as a single, dramatic whole that is "about making four people who barely know one another learn to trust each other."[17]

The first episode was transmitted at 5:16pm on Saturday 23 November 1963. The assassination of John F. Kennedy on the previous day overshadowed the launch of a new television series.[18] It has been written that the transmission was delayed by ten minutes due to extended news coverage; in fact, it went out just eighty seconds late.[19][20] The first episode was repeated a week later, on 30 November, preceding the second episode, "The Cave of Skulls".[18]

The first episode was watched by 4.4 million viewers (9.1% of the viewing audience), and it received a "higher-than-average" score of 63 on the Reaction Index.[18] The repeat of episode 1 reached a larger audience of 6.0 million viewers[21] Across its four episodes, An Unearthly Child was watched by an average of 6 million (12.3% of potential viewers).[18] Episodes 2 - 4 achieved ratings of 5.9, 6.9 and 5.4 million viewers respectively.[21] Mark Bould, however, suggests that a disappointing audience reaction and high production costs prompted the BBC's chief of programmes to cancel the series, until the Daleks, introduced in the second serial in December 1963, were immediately popular with viewers.[22]

The Guardian reviewer Mary Crozier was unimpressed by the serial after the first two episodes, thinking that it "has fallen off badly soon after getting underway". Of the first episodes, she wrote that it "got off the ground predictably, but there was little to thrill". She went on to write that the second part was "a depressing sequel" and the "wigs and furry pelts and clubs and laborious dialogue were all ludicrous".[23] It also received a short favourable review in the Daily Mail, who claimed that it "must have delighted the hearts of the Telegoons who followed".[18]

Retrospective reviews are mainly positive towards An Unearthly Child. Referring to the serial while discussing the early years of Doctor Who, the New Scientist's Malcolm Peltu praised the script, acting and direction, although he was less complimentary about the scenery, which, he says, looks like cardboard.[12]Radio Times reviewer Patrick Mulkern praised the casting of Hartnell, the "moody" direction and the "thrilling" race back to the TARDIS.[24] In 2010, Christopher Bahn of The A.V. Club labelled An Unearthly Child an essential serial to watch for background on the programme.[25] In his review, he noted that the first episode is "brilliantly done; the next three together could be about a half-hour shorter but get the job done". He praised the characters of Ian, Barbara, and the mysterious Doctor, but noted that he was far from the character he would become and Susan was "something of a cipher" with the hope she would develop later.[26]DVD Talk's John Sinnott called the first episode "excellent", but felt the "story goes down hill a bit" with the introduction of the prehistoric time period. He cited the slower pace, the discussions in "Tarzan-speak", and the lack of tension or high stakes.[27] The opening episode's cliffhanger was commended by the Daily Worker,[18] and in 2010, Charlie Jane Anders of io9 listed it among the show's greatest cliffhangers.[28]

To date, the serial has been repeated twice on the BBC, on BBC Two in November 1981, the first full repeat for a Hartnell story screened on the BBC, achieving audience figures of 4.6, 4.3, 4.4 & 3.9 million viewers respectively.[21] It was shown again (with viewing figures of 0.8, 0.7. 0.5 & 0.5 million[29]) as part of the Doctor Who 50th Anniversary, on 21 November 2013, when BBC Four aired the four episodes of a newly restored version concurrently,[30][31][32][33] as did the Horror Channel as part of the Who On Horror season on Good Friday, 18 April 2014.[34]

Writer David Whitaker omitted the An Unearthly Child adventure from the first spin-off novelisation, Doctor Who in an Exciting Adventure with the Daleks (later retitled Doctor Who and the Daleks and Doctor Who - The Daleks), with Ian and Barbara's entrance into the TARDIS leading directly into an adaptation of the second televised serial, The Daleks.[35] Historian James Chapman highlights this as a reason that, in an age before home video, many people believed the Dalek serial to be the first Doctor Who story because the novelisations published by Target Books were the "closest that fans had to the original programmes".[35] Similarly, Cornell et al. report that the second serial overshadowed An Unearthly Child to such an extent that many people believed that Terry Nation (writer of The Daleks) created not only the famous monsters but the entire show itself; this error became so prevalent that it was mistakenly included in an edition of the board game Trivial Pursuit.[36]

Terrance Dicks wrote the Target novelisation of this story, initially published as Doctor Who and an Unearthly Child in October 1981. A French-language version of the novelisation with the title Docteur Who entre en scène (literally, Doctor Who takes the stage) was published in 1987. A 1990 German edition published by Goldmann was one of six Doctor Who novels from that publisher, and was the only one not to feature the Daleks. The German title was Doctor Who und das Kind von den Sternen (Doctor Who and the Child from the Stars). It was the first Target novelisation to feature the "neon logo" and early editions featured a red foil logo. The First Doctor's appearance in the Eighth Doctor Adventures novel The Eight Doctors, also by Dicks, occurs during this story.

A verbatim transcript of the transmitted version of this serial, edited by John McElroy and titled The Tribe of Gum, was published by Titan Books in January 1988. It was the first in what was intended to be a long series of Doctor Who script books.[37]

The story was originally released on VHS in 1990,[38] and the unaired pilot (edited with the second take of the TARDIS scene) was released as part of The Hartnell Years in 1991.[39] The story An Unearthly Child was rereleased and remastered in 2000, with this edition being released only in the UK and Australia.[40] It was remastered again and subsequently released on DVD in January 2006 with The Daleks and The Edge of Destruction in the DVD box set The Beginning, which includes all footage from the pilot (as well as an edited and enhanced 'special edition' of the pilot episode).[41] It was also released in the US and Canada 27 May 2014 as part of An Adventure in Space and Time 3 disc Blu-ray set. The set includes the feature on Blu-ray & DVD and An Unearthly Child on DVD.[42][43]